Combined global positioning system receiver and radio

ABSTRACT

A portable GPS/radio unit ( 10 ) communicates over a wireless radio network ( 12 ) with at least one other such unit. The unit ( 10 ) may transmit radio signals over the network ( 12 ) indicative of the unit&#39;s location. The unit ( 10 ) includes a single, push-to-talk button ( 38 ) that may be pressed to both transmit a voice communication and to initiate transmission of location data. The unit ( 10 ) also includes a “polling” function that requests location data from other units, an auxiliary coding system that codes or encrypts all transmitted data, and an emergency message feature that facilities the transmission and receipt of emergency messages.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radios and global positioning system(GPS) receivers. More particularly, the invention relates to a combinedGPS receiver and radio unit operable for sending GPS-derived data andother information to other such units.

2. Description of the Prior Art

The global positioning system (GPS) is an electronic satellitenavigation system which permits users to determine their position withrespect to the Earth. Global positioning may be determined with ahandheld GPS receiver which detects and decodes signals from a number ofsatellites orbiting the Earth. The signals from each of these satellitesindicate the position of the satellite and the time at which the signalswere sent. To decode the satellite signals, known as spread spectrumsignals, and thereby calculate desired position and navigational data, aGPS receiver must first “find” or acquire the signals emitted from aminimum number of satellites. Once the receiver is “locked on” to thespread spectrum signals, the user's global position and othernavigational data (e.g., velocity of movement) can be calculated.

In addition to the growing popularity and demand for GPS navigationaldevices, portable two-way radios continue to enjoy widespreadpopularity. In 1996, the Federal Communications Commission (FCC)established the Family Radio Service (FRS) so that families and othersmall groups could communicate with one another over very shortdistances (typically less than two miles) at no charge and without anFCC license. The FRS, which is one of the Citizens Band Radio Services,includes 14 channels in the UHF 465 MHz band. There are a number ofcommercially available two-way radios which are designed for use withthe FRS.

The increasing use of both portable radios and GPS receivers has led toproposals to incorporate the two into combined units. It is anticipatedthat such combined units will provide enhanced capabilities such as theability to transmit GPS-derived location data between two or more unitsso that the users of the units may monitor each other's location. Forexample, a family may use several of these combined units to not onlycommunicate with one another but also to monitor each other's locationso that parents may keep track of their children.

Unfortunately, currently-proposed combined GPS/radio units suffer fromseveral limitations that limit their utility. For example, proposeddesigns for combined GPS/radio units include, in addition to the typicalcontrols found on GPS receivers and FRS radios, numerous other buttonsthat must be operated to trigger the transmission of location databetween the units. Those skilled in the art will appreciate that suchadditional buttons complicate operation and increase costs of the units.

Another limitation of currently-proposed combined GPS/radio units isthat location data is only transmitted from a first unit to other unitswhen the user of the first unit elects to do so. This is a problembecause users often wish to know the location of other users, even ifthese other users forget to transmit such information. For example,parents may wish to monitor the location of their children, but only maydo so with currently-proposed units if the children periodicallytransmit their location information back to their parents.

Another limitation of currently-proposed combined GPS/radio units andFRS radios in general is their lack of privacy. Because the FRS is anunlicensed, shared communication service, communications from severaldifferent groups of people are often transmitted at the same time,causing interference. This is especially true in areas where FRS radiouse is popular, such as in amusement parks, sporting events, concerts,etc. Such interference can be avoided to a certain extent by selectingbetween 14 available FRS channels, but often, some or all of thechannels are used simultaneously. Also, once members of a group haveselected a channel and separated from one another, it is difficult toget all of the members to simultaneously switch to a different channel.

To prevent FRS radio users from hearing unwanted radio transmissions,many FRS radios incorporate continuous tone coded squelch systems(CTCSS). A CTCSS controls the audio output of a radio so that users onlyhear desired communications. A CTCSS includes circuitry for generatingand a selector for selecting between a number of sub-audible tones, oneof which is transmitted any time a radio is operating in the CTCSS mode.Other radios with a CTCSS that receive the transmission will disabletheir squelch and therefore enable audio output if they have been set tothe same sub-audible tone. The radios will not disable their squelch forcommunications that are transmitted with a different or no CTCSSsub-audible tone.

Unfortunately, many people incorrectly assume that a CTCSS preventsothers from listening to their conversations. In fact, a CTCSS onlyprevents a user from hearing unwanted conversations, but does notprevent others from listening to the user's conversations. Radios thatdo not have a CTCSS or that have a CTCSS that is turned off can receiveand hear all communications transmitted in their vicinity. For example,a group of users may enable the CTCSS on their radios and communicatewith one another without hearing communications from other people.However, users of other radios without a CTCSS or with a CTCSS that isnot enabled may listen to all of groups' communications. The same istrue for transmitted location data. For example, with prior art combinedGPS/radio units, unauthorized persons may intercept transmitted locationdata and use such data to improperly monitor the location of other radiousers.

Another limitation of currently-proposed combined GPS/radio units andFRS radios in general is that it is sometimes difficult to transmit andreceive emergency messages. FRS rules require users to give priority toemergency messages; however, FRS channels are frequently so crowded thatemergency messages cannot be heard or are interfered with. Moreover,users of radios with a CTCSS as described above cannot hear an emergencymessage unless the CTCSS on their radios is turned off or tuned into thesame sub-audible tone transmitted with the emergency message.

Accordingly, there is a need for an improved combined GPS/radio unitthat overcomes the limitations of the prior art.

SUMMARY OF THE INVENTION

The present invention solves the above-described problems and provides adistinct advance in the art of radios in general, and combined GPS/radiounits in particular. One embodiment of the present invention provides aradio with a single push-to-talk button or other input device that canbe used to initiate transmission of both a voice communication and data.The radio is preferably a combined GPS/radio unit, and the data ispreferably GPS-derived location data. When a user pushes thepush-to-talk button, location data for the unit is automaticallytransmitted either before or after the button is released. This combinestwo important functions in one input device to reduce the complexity andcost of the unit. This also results in the automatic transmission oflocation data every time the user transmits a voice communication.

Another embodiment of the present invention provides a radio with a“polling” function. Particularly, the radio includes a pushbutton switchor other input device that may be pressed to transmit a radio signalrequesting that other users transmit data indicative of their locations.The “polling” request may be simply displayed on the other units or maycause the units to automatically transmit their location data. This“polling” function allows users of the units to monitor each other'slocation even if some of the users forget to transmit their locationdata.

A similar embodiment of the present invention provides a radio thatperiodically automatically transmits a radio signal indicative of itslocation without requiring a user to initiate the transmission. Thisallows a group of radio users to automatically transmit and receiveupdated location information without action from the users.

Another embodiment of the present invention provides a radio having anauxiliary coding system that codes all transmitted location data toprevent unauthorized persons from intercepting the location data andusing such data to improperly monitor the location of the radio. Theauxiliary coding system may be used alone or in conjunction with aCTCSS.

Another embodiment of the present invention includes an emergencymessage feature wherein one CTCSS sub-audible tone is reserved foremergency communications. All radios with this feature have the sameCTCSS tone reserved for emergency communications so that any time anemergency communication is transmitted, all radios in range receive theemergency communication and unmute their radios. The emergencysub-audible tone may be selected from one of the radio's existingsub-audible tones or may be a new, dedicated emergency sub-audible tone.

The inventive features of each of the radios described above arepreferably implemented in a combined GPS/radio unit; however, they mayalso be implemented in other radio and communications devices. Also,although each of the radios described above preferably communicate overthe FRS, they may also communicate over other wireless networks.

These and other important aspects of the present invention are describedmore fully in the detailed description below.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A preferred embodiment of the present invention is described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 is a perspective view of a combined GPS/radio unit constructed inaccordance with a preferred embodiment of the present invention.

FIG. 2 is a block diagram of the components of the GPS/radio unit ofFIG. 1.

FIG. 3 is a block diagram of a communications network linking theGPS/radio unit of FIG. 1 with a plurality of other GPS/radio units.

FIG. 4 is a schematic representation of a display on the GPS/radio unitof FIG. 1, wherein the display indicates the location of multipleGPS/radio units on an electronic map.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawing figures, and particularly FIGS. 1 and 3, aportable radio 10 constructed in accordance with a preferred embodimentof the invention is illustrated. The radio 10 is preferably a combinedGPS/radio unit that may transmit and receive voice communications,determine its location using the GPS, and transmit location data toother such units 10A, 10B, 10C, 10D and 10E over a wireless network 12.In the preferred embodiment of the present invention, units 10 and10A–10E communicate with one another over a public radio network such asthe Family Radio Service. While six units 10 and 10A–10E are shown onthe exemplary embodiment of FIG. 3, only two such units are necessaryfor the purposes of the present invention.

Referring to FIGS. 1 and 2, the preferred unit 10 comprises a GPSreceiver 14, a GPS antenna 16, a radio transceiver 18, and a radioantenna 20 all mounted in or on a radio housing 21. The GPS receiver 14is electronically coupled with a processor 22 which has an associatedmemory 24 for storing information such as cartographic data (i.e.,electronic maps). Similarly, the radio transceiver 18 is coupled withthe processor 22 and a data modem 26. The data modem is used fortransmitting and receiving data such as location data as describedherein. The cartographic data may be stored on cartridges which can beremovably attached to the unit 10. For example, an electronic map of aparticular city or national park may be stored in a single cartridge.The memory 24 may also store historical location data for the unit 10 orfor other units which have transmitted location data to unit 10. Theantennas 16, 20 preferably extend upwardly from the top of the housing21.

The unit 10 also includes a microphone 28, a speaker 30, an input 32,and a display 34. The microphone 28 and the speaker 30 are conventionaland may be, for example, the same type of microphone and speakerequipped with a standard FRS radio. The display 34 is preferably aliquid crystal display (LCD) and is used to display location informationand cartographic data as described in more detail below.

The input 32 is preferably an alphanumeric keypad, such as a telephonekeypad, which may be used to select and input a name or other identifierfor the unit 10 using any combination of the letters, numbers, orsymbols which are available on the keypad. The keypad may include anynumber of control buttons such as the twelve buttons standard on atelephone keypad. As will be understood, the input 32 could be somethingother than a keypad, such as a microphone/voice recognition input, atouch screen, or a menu-driven display input.

The unit 10 also includes a continuous tone coded squelch system (CTCSS)36 and a push-to-talk button 38. The CTCSS 36 controls the audio outputof the speaker 30 so that only certain desired communications are heardby a user of the unit 10. The CTCSS 36 includes circuitry for creating aplurality of sub-audible tones and a selector for selecting one of thetones. The selector may be a key or button on the input 32 or adedicated key or button positioned elsewhere on the unit 10. Whenenabled, the CTCSS 36 transmits the selected sub-audible tone with allvoice communications. Other nearby units 10A–10E will receive thesub-audible tone along with all transmitted voice communications anddisable their squelch if they have a similar CTCSS 36 that has been setto the same sub-audible tone. This allows a group of users to set theirunits to the same sub-audible tone and then communicate with one anotherwithout hearing communications transmitted by radios with a different orno CTCSS 36 sub-audible tone. However, as described above, other radioswith no CTCSS 36 or with a CTCSS 36 that is turned off will still beable to listen to all communications transmitted over the FRS.

The push-to-talk button 38 may be any conventional pushbutton switch orother control device normally found on FRS radios and operable totransmit voice communications. However, in accordance with one importantaspect of the present invention, the push-to-talk button 38 is coupledwith the processor 22 to combine two important functions in a singlebutton. Specifically, the push-to-talk button 38 is operable to bothinitiate transmission of voice communications and transmission of aradio signal indicative of a GPS-derived location of the unit.

When a user presses the push-to-talk button 38 and begins speaking intothe microphone 28, the radio transceiver 18 begins transmitting a voicecommunication along with the selected CTCSS 36 sub-audible tone in aconventional manner. Pressing the push-to-talk button 38 also triggersthe transmission of a radio signal with GPS-derived location dataindicative of the location of the unit 10. By combining both functionsin a single input device, operation of the unit 10 is simplified.Moreover, this arrangement allows updated location data to beautomatically transmitted each time the user transmits a voicecommunication. The push-to-talk button 38 may also initiate transmissionof data other than the location data.

In preferred forms, the location data or other data is transmitted afterthe push-to-talk button 38 has been pushed and then released so that thedata does not interfere with transmitted voice communications. In thisembodiment, the processor 22 preferably keeps the radio transceiver 18enabled for a pre-determined time interval after the push-to-talk button38 has been released to permit transmission of the location data. Forexample, the radio transceiver 18 may remain enabled to transmit thelocation data for approximately 100–300 milliseconds after thepush-to-talk button 38 has been released. This provides ample time fortransmitting the location data while minimizing any possibility that theuser will interfere with transmission of the location data by pressingthe push-to-talk button 38 too quickly.

Similarly, if the unit 10 is receiving a voice communication and acorresponding CTCSS 36 sub-audible tone from another unit, the processor22 keeps the radio transceiver 18 enabled for a pre-determined amount oftime after the processor detects loss of the received CTCSS 36sub-audible tone so that the radio transceiver 18 may continue listeningfor location data from the other unit. The pre-determined time intervalis preferably the same as when the radio transceiver 18 is transmittinglocation data (i.e., 100–300 milliseconds).

In another embodiment of the push-to-talk feature, the location data istransmitted immediately after the push-to-talk button 38 is firstpressed. In this embodiment, the processor 22 and the radio transceiver18 preferably transmit the location data within a pre-determined timeafter the push-to-talk button 38 has been pressed to minimizeinterference with subsequent voice communications. The pre-determinedtime may be, for example, 100–300 milliseconds.

In another embodiment of the invention, the unit 10 includes a “polling”function that enables a user of the unit 10 to request locationinformation from the other units 10A–10E. Particularly, the unit 10includes a button or other input device coupled with the processor 22that may be pressed or otherwise operated to cause the unit 10 totransmit a radio signal over the network requesting the other units10A–10E to transmit location data over the network. The polling buttonor input device may be a key or keys on the input 32 or may be adedicated key or button positioned elsewhere on the unit 10. The“polling” request may be displayed on the other units or may cause theother units to automatically transmit their location over the network 12so that the unit 10 and all other units may receive it.

In another similar embodiment of the invention, the unit 10 may beconfigured to automatically send a radio signal indicative of itslocation over the network 12 at periodic intervals. This feature enablesall units 10, 10A–10E to automatically receive updated location datafrom the other units without user action.

In another embodiment of the invention, the unit 10 includes anauxiliary coding system that codes or encrypts all location data priorto transmission. The auxiliary coding system may use any known coding orencryption scheme such as public or private key encryption methods. Forexample, a group of radio users may each enter an agreed-upon 8-bit codeinto their radios prior to use. The processor 22 then uses the 8-bitcode to encrypt transmitted location data and to decrypt received data.The auxiliary coding system is preferably used in conjunction with theCTCSS 36 described above to prevent a user of the unit 10 from hearingunwanted conversations and to prevent unauthorized persons fromintercepting transmitted location data. Thus, a user of the unit 10wishing to transmit a message first selects a desired channel, then aCTCSS 36 sub-audible tone, and finally an encryption code. This providesseveral layers of security or privacy that together prevent users fromhearing unwanted communications and prevent unauthorized persons fromimproperly tracking the locations of other radio users. This embodimentof the invention may be particularly useful for groups of users who areparticularly concerned with privacy, such as law enforcement groups.

In another embodiment of the invention, the unit 10 includes anemergency message feature that makes it easier for users to transmit andreceive emergency messages. The emergency message feature reserves oneof the CTCSS 36 sub-audible tones for emergency communications. TheCTCSS 36 of the units 10, 10A–10E are always tuned to this emergencysub-audible tone as well as any other tones selected for normal voicecommunications. Thus, any time an emergency communication istransmitted, all radios in range of the message will receive the messageand unmute their speakers even if their CTCSS 36 is set to anothersub-audible tone for regular, non-emergency messages. The emergencysub-audible tone may be selected from one of the radio's existingsub-audible tones or could be a new, dedicated emergency sub-audibletone.

The emergency message feature also preferably includes an emergency callindicator 40 coupled with the processor 22. The emergency call indicatoris actuated each time the processor 22 senses receipt of the emergencysub-audible tone to alert the user that an emergency message is about tobe received. The emergency call indicator 40 may be an indicator light,tone, vibration device, or any other device capable of alerting a userof receipt of an emergency call.

In use, the unit 10 communicates with other GPS/radio units (e.g., units10A–10E) over the wireless network 12 in the same manner thatconventional two-way radios communicate with one another. In addition,these units are able to calculate their location and communicate thatlocation data to one another since they are also equipped with GPSreceivers. Transmission of the location data may be triggered by thepush-to-talk button 38 as described above. Another way to communicatethe location data over the wireless network 12 is to divide theavailable bandwidth into a voice portion and a data portion so thatvoice and data may be communicated simultaneously. If only a smallportion of the bandwidth is allocated for data transmission, thereshould be no noticeable degradation of the voice communication.Alternatively, the entire communication channel could be used for voicecommunication except for periodic interruptions during which a burst oflocation data is sent. If the period of the interruption is short, thereshould be no noticeable effect on the quality of the voicecommunication. The data may be transmitted using one of a variety ofdifferent modulation techniques, including frequency shift keying (FSK),minimum shift keying (MSK), or phase shift keying (PSK).

FIG. 4 is a schematic representation of an exemplary display 34 on theunit 10 in which the display 34 indicates the location of four differentGPS/radio units. Although darkened circles are used in FIG. 4 toindicate the location of the four units, any other location designatorcould be used. The display 34 also indicates a unique alphanumericidentifier for each of the four units. For example, the identifiers A1,A2, A3, and A4 may correspond to units 10A, 10B, 10C, and 10D, in whichcase the location of unit 10 would not be shown. Alternatively, theidentifier A1 may correspond to unit 10 and the identifiers A2–A4 maycorrespond to units 10A–10C so that the location of unit 10 is shown onits display 34. While alphanumeric identifiers were selected in theexample of FIG. 4, any available identifier (or combination ofidentifiers) could be used (e.g., letters, numbers, symbols, icons,colors, etc.) for the units. Moreover, an identifier could perform thedual function of identifying the unit and of indicating the location ofthe unit, thus eliminating the need for a darkened circle or other suchlocation designator.

There are many practical applications which could utilize the advantagesof the present invention. For example, if a family or other small groupis camping or hiking and each person is carrying a GPS/radio unit, theneveryone can communicate with one another and see where everyone else islocated. Since each person's position would be indicated on theelectronic map displayed on each of the units, the other members of thegroup could quickly locate a member who becomes lost or injured. Thiswould also be the case if the group is located in an urban orresidential area.

Although the invention has been described with reference to thepreferred embodiment illustrated in the attached drawing figures, it isnoted that equivalents may be employed and substitutions made hereinwithout departing from the scope of the invention as recited in theclaims.

1. A portable radio capable of communicating with at least one otherportable radio over a wireless radio network, the radio comprising: aradio transceiver for transmitting voice communications to and receivingvoice communications from the other radio; and a continuous tone codedsquelch system (CTCSS) coupled with the radio transceiver forcontrolling audio output of the transceiver so that a user of the radioonly hears certain communications transmitted over the network, theCTCSS including a selector for selecting between a plurality of CTCSStones that each, when selected, is transmitted by the radio transceiverand received by the other radio and used to enable audio output of theother radio only if the other radio has been set to the same CTCSS tone,the CTCSS further including an emergency CTCSS tone that, when selectedand transmitted, enables the audio output of the other radio whether ornot the other radio has been set to the same CTCSS tone as the radio. 2.The radio as set forth in claim 1, wherein the emergency CTCSS tone isselected from existing CTCSS tones.
 3. The radio as set forth in claim1, wherein the emergency CTCSS tone is a new tone added to the CTCSS. 4.The radio as set forth in claim 1, further including— a GPS receiver forreceiving satellite signals from a plurality of satellites; and aprocessor coupled with the GPS receiver for calculating a location ofthe radio as a function of the satellite signals.
 5. The radio as setforth in claim 4, wherein the voice communications and the location aretransmitted simultaneously.
 6. The radio as set forth in claim 4,wherein the location is transmitted so as to not interfere withtransmission of the voice communications.
 7. The radio as set forth inclaim 4, wherein the location is encrypted according to a user definableencryption code.